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Topic Title: Storage heater burns..what temperature?
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Created On: 23 September 2017 07:36 PM
Status: Read Only
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 Storage heater burns..what temperature?   - terryJo - 23 September 2017 07:36 PM  
 Storage heater burns..what temperature?   - broadgage - 25 September 2017 09:27 AM  
 Storage heater burns..what temperature?   - OMS - 25 September 2017 12:41 PM  
 Storage heater burns..what temperature?   - electric - 26 September 2017 10:42 AM  
 Storage heater burns..what temperature?   - sparkingchip - 26 September 2017 11:17 AM  
 Storage heater burns..what temperature?   - rogerbryant - 26 September 2017 11:49 AM  
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 23 September 2017 07:36 PM
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terryJo

Posts: 2
Joined: 23 September 2017

Hi all,

I have a client who has burned himself rather badly on an old storage heater..think its a Creda one and they want me to confirm if the heater is faulty or not.

I took a look at it and the first thing I found was the DP switch was reverse polarity so it would of been switching the neutral...as I understand it the input stat would of still worked and the thermal overload cut out should of still worked?

I have isolated it for now but am planning on returning, connecting it to the 24/7 supply, letting it heat up for a couple of hours then taking a measurement of the casing temperature. Does anyone know what the max temperature should be of a storage heater?

Thanks
Terry
 25 September 2017 09:27 AM
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broadgage

Posts: 2452
Joined: 07 August 2007

Can a double pole switch have reversed polarity ? surely both poles of the supply are switched anyway.
Reversed polarity on the internal wiring should not cause overheating.

IME, old storage heaters that have been re-located often have excessive external temperature because the insulation material has been lost, broken, or not installed correctly.
This also prevents the heater from working correctly since most of the heat escapes early in the day rather than being saved for later.

Some storage heaters have an input control, that alters the temperature to which the heater is "charged" double check that this is not stuck, jammed, forced beyond the intended range etc.

Presumably the burnt victim was in normal physical and mental health ? Even relatively low temperature heat sources can cause burns if disability results in prolonged contact.
A fire guard or railing such as used for an open fire or wood burning stove may be required in such cases.
 25 September 2017 12:41 PM
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OMS

Posts: 22433
Joined: 23 March 2004

Typically the case temperature should be limited to 80C or 70C if you expect people to be touching it - but not holding it

For safety, most guidance for avoidance of burns to vulnerable people would limit case temperatures to 43C

Old storads simply can't comply with the latter, and usually don't comply with the former

Table 42.1

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 26 September 2017 10:42 AM
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electric

Posts: 44
Joined: 04 June 2009

Hello terry Jo.

Something else for you to check.

The case temperature of a fully charged older storage heater will be far hotter than a person could withstand touching, other than momentarily. Along with the input charge control that broadgage describes their is also often an output control.

The output control operates a flap inside the heater which releases heat from the core. In normal operation it should not be possible to have the flap open when the heater is charging, or until the core temperature has depleted to a safe level. Depending upon heater make and model the operation of the flap is controlled by a bimetallic strip or thermal hydraulic activation which work in conjunction with the output control knob. When the storage radiator is charging a small accelerator heater acts upon the flap's control mechanism to ensure it closes until the temperature in heater rises. Correctly set, the flap's mechanism should not allow the flap to open until the heater's core temperature depletes to a safe level, and from that point, depending upon how the output knob is set, will control how quickly the remaining heat within the heater is let out.

If ether the flap closing accelerator is not operating, or the any of the output control mechanism components are stuck/failed, then the flap can remain permanently open, or open prematurely, either of which will cause the top part of the heater's casing to become extremely hot.

It has long been recognised that storage heater case temperatures can be a problem when the heaters are used in certain environments. They are companies that make purpose built guards. A quick web search should reveal them.

Hope the foregoing may be of some assistance to you.

-------------------------
Kind regards, Chris
 26 September 2017 11:17 AM
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sparkingchip

Posts: 10180
Joined: 18 January 2003

Presumably the customer is accustomed to the normal heat of the heater if it is old and the same customer has used it for a number of years, so knows when it is too hot.

Sounds like a faulty thermostat that has allowed the heater to charge for the full off peak period with the time clock then turning it off rather than the thermostat, but before the thermal fuse blew.

Andy B
 26 September 2017 11:49 AM
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rogerbryant

Posts: 980
Joined: 19 July 2002

As rough guidance at 40°C a burn will appear in 4hrs (hence the 43°C for vulnerable people) at 100°C a burn will appear after 4 seconds.

Best regards

Roger
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